The present application is based on Japanese Priority Document 2000-215691 filed on Jul. 17, 2000, the content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a wire dot printer and a wire dot printer using the same.
2. Discussion of the Background
There is already provided in the related art a wire dot printer head in which a plurality of cores and yokes arranged in an annular shape are integrally formed by magnetic material, a coil is fitted to each of these cores, a plurality of armatures having wires fixed at their extremity ends with means such as a brazing and the like are arranged in a radial form, and supported so as to be raised or lowered in respect to the cores, the extremity ends of the wires are arranged in rows by the extremity end guides to be slidably supported. Such a wire dot printer head as above is moved in a main scanning direction in parallel with the platen while being mounted on a carrier, the specified coil is excited during its moving process to drive the armature and then the extremity ends of the wires are struck against the printing medium on the platen to perform a printing operation.
As shown in FIG. 6, an extremity end guide 100 having a plurality of guide holes 100a arranged on a linear line of one row is applied and when the extremity ends of the wires are arranged in rows by the extremity end guide 100 on a linear line extending along a sub-scanning direction Y crossing at a right angle with a main scanning direction X acting as a moving direction of the wire dot printer head, for example, when an alpha-numerical letter of xe2x80x9cIxe2x80x9d is printed, the wires arranged in the sub-scanning direction Y must be driven at once. With such an arrangement as above, there occurs a problem that the capacity of power supply is increased and noise generated when the wires strike against the platen is increased.
In view of this fact, as shown in FIG. 7, there is provided a system in which an extremity end guide 101 having a plurality of guide holes 101a divided into two rows and arranged in a zig-zag form is applied, the extremity ends of the wires are arranged in two-divided rows along the sub-scanning direction Y, the extremity ends of the wires are arranged in a zig-zag form in such a way that the arranging positions of the wires in the first row and the wires in the second row along the sub-scanning direction Y may be displaced only by a pitch corresponding to a half of a diameter of the wire, and even in the case that the letter of xe2x80x9cIxe2x80x9d is to be printed, after the entire wires in the first row are driven, the wire dot printer head is moved in the main scanning direction X only by a space between the wires in the first row and the wires in the second row, the entire wires in the second row are driven to cause one character or letter to be printed in two separate stages (refer to the gazette of Japanese Patent Laid-Open No. Sho 54-24115).
Further, there is also provided a system enabling the similar object to be accomplished in which as shown in FIG. 8, an extremity end guide 102 having a plurality of guide holes 102a arranged along two arcs is used and the extremity ends of the wires are arranged along the two arcs (refer to the gazette of Patent No. 2958010). Further, although not shown, there are provided two proposals, one of them being such that the extremity ends of the wires are arranged along a contour of rhombus and the other being set such that the extremity ends of the wires are arranged on a linear line inclined in a synthetic direction between the sub-scanning direction and the main scanning direction.
In the case of the structure in which the extremity ends of the wires are divided into to rows and arranged in a zig-zag form or in the case of the structure in which the extremity ends of the wires are arranged along the two arcs or arranged along a contour of rhombus, a work for inserting the extremity ends of the wires into the respective guide holes formed in the extremity end guide while bending the wires which is to be apt to extend straight is quite troublesome. This is due to the fact that it is quite hard to adjust a degree of bending to keep the space of specified size and specified shape inside the plurality of bundled wires when the plurality of wires are bent to be bundled from outside.
In the case that the number of intermediate guides supporting the intermediate part of the wire between the rear end of the wire fixed to the armature and the extremity end guide for supporting the extremity end of the wire is increased, it is possible to guide the wire in sequence from the intermediate guide at the armature side to a subsequent intermediate guide in sequence. However, in the case where the number of intermediate guides is increased and the extremity ends of the wires are to be accurately guided into the intermediate guide, the independent guide hole must be formed accurately at the intermediate guide and its cost will be increased. Further, since a load is applied from the intermediate guide to the wires, so the wires are prevented to move in high speed.
Further, in the case of the structure in which the extremity ends of the wires are arranged along the two arcs or arranged along a contour of rhomb, the number of wires having different arrangement position in the main scanning direction is increased, so that in order to drive the coil corresponding to the wire having different arrangement position in the main scanning direction under a different timing, more number of control circuits are required and the voltage applying control becomes complicated. In particular, in the case of structure in which the extremity ends of the wires are arranged on a linear line inclined in a synthetic direction between the sub-scanning direction and the main scanning direction, the positions of main scanning directions of all the wires are different from each other, whereby the number of control circuits corresponding to the number of wires is required and the voltage applying control becomes most complicated.
It is an object of the present invention to keep a power supply capacitance, reduce noise, improve assembling workability and reduce cost.
The object of the present invention is achieved by the novel wire dot printer head and wire dot printer of the present invention.
According to the novel wire dot printer head of the present invention, the extremity ends of a plurality of wires supported at a free end of an armature so as to be driven and displaced are slidably supported by the guide holes formed at the extremity end guides in an independent manner and arranged. In the case where the moving direction of the wire dot printer head is as the main scanning direction, the guide holes at the extremity end guides are arranged along the arc (in a continuous manner) curved only in one direction of the sub-scanning direction so as to cause the arrangement position in the main scanning direction to be different while satisfying a condition in which all the arrangement positions of the sub-scanning direction crossing at a right angle with the main scanning direction are different.
According to the novel wire dot printer of the present invention, the free end of the armature is provided with a wire dot printer head for supporting a plurality of wires to be driven. The extremity ends of the plurality of wires are slidably supported by the guide holes arranged at the extremity end guides in an independent manner and arranged. In the case where the moving direction of the wire dot printer head is applied as the main scanning direction, the guide holes at the extremity end guides are arranged along the arc curved only in one direction of the sub-scanning direction (in a continuous manner) so as to make the arrangement position in the main scanning direction different while satisfying a condition in which all the arrangement positions of the sub-scanning direction crossing at a right angle with the main scanning direction are different. A voltage is applied to the coil for driving respective wires in response to the arrangement position of the wire extremity ends in the main scanning direction while changing its timing.